natbib: custom biblabel ignores leftmargin

Question

1. Main question; left margin: This answer provides the code to style the bibliography label in a desired fashion. However, the new biblabel ignores the left margin of the page. Since I do not really understand what the code snippet does I'm not able to adapt it to my needs. NOTE: actually I would like to use this answer to the same question (it suppresses the hyperlink in the biblabel), but unfortunately I can not make it work with my MWE while it works fine with my actual tex document.

2. Secondary question; bold biblabel: The biblabel should be bold to match the desired bibstyle. a slightly modified abbrvnat.bst is used, the MWE with abbrvnat should be ok as example, as far as I understand...

MWE:

\documentclass[11pt]{article}

% bibliography
\usepackage[square,sort&compress]{natbib}
\bibliographystyle{abbrvnat}
\setlength\bibhang{1cm} % adjust 2nd(+following) line indentation

% hyperlinks in PDFs
\usepackage[colorlinks=true,citecolor=blue]{hyperref}

% generate bibfile                          
\usepackage{filecontents}
\begin{filecontents}{references.bib}
@ARTICLE{Author1900,
  author = {Author, Andrew and Author, Burt},
  title = {Very short Title},
  journal = {Best Journal},
  year = {1900},
  volume = {1},
  pages = {1--3},
  number = {7},
  month = jan,
  issn = {1234-5678},
  publisher = {Best Publisher Ltd.},
  timestamp = {1900.01.01},
  url = {www.nonsense.url}
}
\end{filecontents}

% set format of bibitem in reference list
\makeatletter
\def\@lbibitem[#1]#2{%
   \if\relax\@extra@b@citeb\relax\else
      \@ifundefined{br@#2\@extra@b@citeb}{}{%
        \@namedef{br@#2}{\@nameuse{br@#2\@extra@b@citeb}}}
   \fi
   \@ifundefined{b@#2\@extra@b@citeb}{\def\NAT@num{}}{\NAT@parse{#2}}%
   \item[\hfil\hyper@natanchorstart{#2\@extra@b@citeb}%
      \citep{#2}%
      \hyper@natanchorend]%
   \NAT@ifcmd#1(@)(@)\@nil{#2}}
\makeatother


\begin{document}

This is a simple citation \citep{Author1900}.

\bibliography{references}

\end{document}